Rheostat for aircraft panel light control



ited m Pat Ofii 'RHEOSTAT FOR AIRCRAFT PANEL CONTROL Theodore H.Projector, Forest Glen, Md.

No Drawing. Application July 8, 1953, Serial No. 366,882

2 Claims. (Cl. 20-62) (Granted under Title 35, U. S. Code (1952), sec.266) The present invention relates to rheostats or other electricalcomponents to be used in aircraft instrument panels 01 in othercircumstances where panel space is limited.

It is an object of this invention, therefore, to provide a rheostat orpotentiometer of the wire-wound type having a small size and compactconstruction and in which the wire forming the resistance element issmoothly contacted by a moving element with a wiping action.

It is a further object of this invention to provide a rheostat, or otherelectric component, of the wire-wound type having a moving slider with apair of contacts, one of said contacts making an electrical connectionwith the rheostat windings, the other of said contacts moving along aconductive collecting strip.

Another object of this invention is to provide an adjustable rheostat ofthis character which is operated in an extremely simple and convenientmanner and which is susceptible of quantity production with economy andfrom materials and by means ordinarily available.

It is also an object to provide a variable resistive element which maybe used as a rheostat, voltage divider, or

as an ordinary variable resistance.

Generally, in practicing this invention, a slider, having a pair ofcontacts, is moved by rotation of a threaded or grooved rod which ismounted inside an insulated tubular form. The slider is a conductivecollar whose inner surface is machined so as to fit into the spirallygrooved rod in such manner that rotation of the rod moves the contactarms along the length of the tube, one of said contacts travelling alonga slot in the tube and contacting the turns of a bared wired coil, theother of said contacts travelling along a longitudinal groove andcontacting a collecting strip.

Other objects and advantages reside in certain novel features ofconstruction, arrangement and combination of parts which willhereinafter be more fully described and Referring to the drawings itwill be seen that the rheostat comprises a tubular form 11, composed ofan insulating material. The form 11 is provided with a longitudinal slot28, and a longitudinal groove having a conductive collecting strip 12therein. A rheostat winding 10 is wound on the form 11, the windings 10being bared on the bottom surface, or at least on the surface directlyopposite the slot 28. An actuating rod 13 provided with a spiral groove14 is supported within the form 11.

The form 11 is mounted on the support member 16 on which is provided anintegral screw member 19 and a locking nut 18 used for locking therheostat in position ill) 2,707,811 Patented May 10, 1955 26 by asinsulated bearing member 27 and at its rather end by the journal 29. Theactuating rdd is also are: vided with a knob or handle 17 forfacilitating manual rotation.

A slider 15 is mounted on the actuating rod 13. The slider 15 is aconductive collar, the inner surface of which is machined so as to fitonto the spiral grooves 14. The slider 15 is provided with a springcontact 21 adapted to ride on the conductive strip 12, and a springcontact 20 adapted to move within the slot 28 and to wipe across thebared turns of the winding 10. The slider 15 is also provided with a lug22 which rides in the slot 28 and prevents rotation of the slider.

The electrical terminals 23 and 25 are provided at each end of thewinding 10 while a terminal 24 is provided at the collecting strip 12.

Thus, when the rod 13 is manually rotated by the knob 17, the slider 15will be caused to travel along the rod and the contacts 20 and 21 willwipe the windings 10 and the collecting strip 12. By connecting a sourceof potential across the terminals 23 and 25, and by employing theterminals 24 and 25 as output terminals the instrument may besatisfactorily employed as a voltage divider, the output of the dividerbeing determined by the position of slider 15, the output being tappedfrom the winding 10 by the contact 20 to the conductive slider 15 and tothe contact 21, the conductive strip 12, and to the terminal 24.

The instrument may also be employed as a simple variable resistor bymerely connecting the terminals 24 and 25 in a circuit to be controlled,a circuit then being completed from the terminal 25 through a portion ofthe winding 10, the contact 20, the slider 15, the contact 21, theconductive strip 12 and to the terminal 24.

It is also clear that the actuating rod 13 may be provided with avariable pitch groove or thread to obtain a non-linear output.

While I have shown and described a rheostat in which the invention maybe advantageously embodied, it is to be understood that thisconstruction has been selected merely for the purpose of illustrationand that various changes in size, shape and arrangement of parts may bemade without departure from the spirit or scope of this invention.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

1. A variable electrical component comprising a hollow cylindricalinsulated form having a longitudinal slot therein and having alongitudinally disposed conductive collecting strip mounted on the innersurface thereof; a continuous winding wound on said form; a spirallygrooved actuating rod supported longitudinally within said form; aslider mounted on said rod, said slider comprising a conductive collarhaving an inner surface adapted to fit said spirally grooved actuatingrod; a first spring contact on said slider adapted to contact saidcollecting strip; a second spring contact on said slider adapted to wipesaid winding above said slot; means for rotating said rod; andadditional means on said slider cooperating with said longitudinal slotto prevent rotation of said slid-er.

2. A variable electrical component comprising in combination a hollowcylindrical insulated form; a longitudinal slot in said form; aconductive collecting strip mounted along the length of the innersurface of said form; a screw mounted within said form for rotation ineither direction; an internally threaded conductive collar lar adaptedto contact said collecting strip; a second spring contact on said collaradapted to extend through said longitudinal slot in said form; a lengthof wire spirally wound on said form, said wire having its portionsopposite said slot bare of insulation; and a lug fixed to said collarand projecting into said longitudinal slot for preventing rotation ofsaid collar.

References Cited in the file of this patent UNITED STATES PATENTSCederquist Oct. 7, 1924 Collins Aug. 9, 1932 FOREIGN PATENTS GreatBritain Jan. 28, 1926

